Thorn Cycles Forum

Had a problem with my Raven Tour last week. Broke a spoke on the front wheel after 7300km. I decided to re-spoke the whole wheel which was a very wise move. Every single spoke had gone very brittle and snapped with very light pressure. Most went whilst removing them from the rim. I decided that I had better re-build the rear wheel as well, and chose to fit an Andra CSS rim (because i could!) at the same time. Rear wheel had absolutely no brittle spokes. All good and solid. I rebuilt anyway as I had brought the parts!

Has anybody else experienced this type of issue (brittle spokes) with Sapim? The spokes look like they had corroded through...

The bike had been in storage since November 2017. It was washed and lubed before being put away. I'm just glad that I didn't hit a pothole when I took it out. I have never seen a set of spokes do that. They were originals that came new with the bike. They can only have been a bad batch. If so, somebody else must have experienced this!

I think there was a bad batch of steel or some other problem some time back. I did a quick search and found this link too.http://thorncyclesforum.co.uk/index.php?topic=10885.0

I see that I made a few comments at that other thread too.

I live in USA, Sapim spokes are pretty rare here, thus I use a different brand. I have nothing against Sapim, in fact I used Sapim nipples on the last two sets of wheels I built. But I usually use Wheelsmith spokes, they are made 90 miles from my home.

Hi Mickeg, That sounds exactly the issue. The spokes seem to break anywhere. You can take half of one that is already broken and easily snap that piece in half, and then snap those pieces again in your hands using no tools. They are a bit like dried spaghetti! Obviously the combined strength of the 32 in the wheel was sufficient to get me the 8 miles I managed (and the remaining 31 the return journey.)

Unlikely to be a factor in this case, but bikes stored near chlorinated swimming pools or in sheds with pool materials tend to suffer; the chlorine embrittles the stainless spokes. Some are more susceptible to this kind of damage than others.

Unlikely to be a factor in this case, but bikes stored near chlorinated swimming pools or in sheds with pool materials tend to suffer; the chlorine embrittles the stainless spokes. Some are more susceptible to this kind of damage than others.

Best,

Dan.

I knew that Chlorine and stainless steel did not play well together but I had never heard that low levels of Chlorine in the air from something like a nearby swimming pool could be at high enough concentrations to cause damage. Interesting.

As a side note, if I recall correctly Thorn uses marine grade stainless fasteners to better resist corrosion.

Here are some outside links that describe this failure mode:https://www.bikeforums.net/bicycle-mechanics/886339-strange-spoke-breakage-problem.htmlhttp://forums.roadbikereview.com/wheels-tires/broken-spoke-mid-spoke-349592.htmlhttps://groups.google.com/forum/#!topic/rec.bicycles.tech/azhAOJjr9Qkhttps://endless-sphere.com/forums/viewtopic.php?t=58583&start=50QuoteI knew that Chlorine and stainless steel did not play well together but I had never heard that low levels of Chlorine in the air from something like a nearby swimming pool could be at high enough concentrations to cause damage. Interesting.I think it may depend on the amount of ventilation available, how concentrated the fumes can become, and the length of exposure.

Chlorine bleach can also damage spokes. I knew a school janitor whose wheels started and kept breaking spokes. Turns out he stored his bicycle in the maintenance closet with the chlorine bleach. After cleaning the toilets and mopping the floors, there was always some in the bucket at that end of the closet. The bike was fine for a long time -- years -- but eventually, the front spokes (wheel closest to the bucket) failed. Wasn't till I saw where and how the bike was parked that I figured it out. The spokes never failed thereafter, but it is hard to say why because the spokes were a different brand and the bike was parked elsewhere (the gentleman retired).

Sapim had a bad batch a few years back that caused a few wheel builders problems, it's resolved now, although there may still be some old stock kicking about.I've built a lot of expedition wheels using Sapim spokes and never had a failure or anyone complain of spoke breakages on tour using my wheels.These things happen occasionally.

I think there was a bad batch of steel or some other problem some time back. I did a quick search and found this link too.http://thorncyclesforum.co.uk/index.php?topic=10885.0

<snip>

Yep, that was me!

Gíday everyone. I havenít been on this forum for awhile. Itís good to be back!

The spoke failure Tony described is exactly what I was experiencing, and with Sapim Race spokes as well. Back in 2014-15, I went through three complete wheel builds for both wheels on my Nomad (a year to two years after they were built). I finally switched to DT Swiss, and (touching wood) have had great wheels since, including on some fully loaded, very rough off-road touring.

I have never claimed it was a Sapim vs others issue, although I was dark on Sapim for sending me Force replacements, rather than Race, which I couldnít use because they were out of spec for both Rohloff and SON (notwithstanding that they were sent free, no questions asked, so they were very aware of the issue). They ignored me when I sought to swap them out for Race, as originally requested. I donít know if they thought I was being ungrateful, as they were sending ostensibly stronger spokes all the way to Australia, but when I didnít get a response to my issue I just went elsewhere.

By all accounts, other manufacturers also experienced this, but Sapim was by far the most frequent.

Tony, I would contact Sapim, and ask them specifically to replace your spokes with identical ones. Iíd be very surprised if this issue persists with anything in stock with them.